Buffing and polishing composition



Patented Nov. 26, 1946 BUFFIN G AND POLISEING COMPOSITION Samuel S. Kistier, Worcester, Mass, assignor to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware Ne Drawing.

Application January 5, 1938,

Serial No. 183,455

5 Claims.

This invention relates to bufing and polishing compositions having a mildly abrasive action, which composition is particularly suited to the cleaning and polishing of smooth hard surfaces.

Many compounds have been previously used. for the purposes of buffing and. polishing, but it has generally been necessary to choose from the known abrasives one suited to work at hand. For the finer types of .polishing the most generally used materials are rouge, pumice, talc, and the like. I have discovered a class of compounds which is capable of almost infinite variation in nature from which class may be chosen an abrasive having the properties required for a particular type of work.

There is disclosed in my prior Patent No. 2,093,- 454, dated September 21, 1937, an aerogel produced by precipitating a colloidal substance, such as silica, in a liquid as a gel, confining the resulting product in an autoclave, and heating the same until the liquid in the gel has reached a temperature at which the surface tension of the liquid is so small as to produce no substantial shrink age of the gel when the liquid is allowed to evaporate, and then slowly releasing the vapor from the autoclave so as to not injure the internal structure of the gel. In this way the skeleton structure of the gel is preserved approximately in its original porous state and the product is alight fiuffy powder, the void spaces of which may range from the usual 30 to 50% found in all commercial gels, up to 99 %"or higher.

Aerogels may be produced from other gels:

whether elastic or inelastic by similar processes.

The aerogels are extremely porous, and although no voids can be seen when the substance is viewed with a microscope, the apparent density of the aerogels is generally well below of the actual density. The high degree of porosity of these materials renders them excellent carriers for substances to be used in conjunction therewith during bufling or polishing. If an oily or greasy material is used with the aerogel, it will be found 1 that it is readily washed off with water by reason:

of the emulsifying action of the aerogel.

The emulsifying action of the aerogel may be layer of wax on thesurface of the silver resulting from breaking of the emulsion. The wax will act to enhance the appearance of the surface and also to inhibit tarnishing when not in use.

It has been found that an aerogel produced in 5 accordance with the teaching of the above patent when mixed with a heavy oil, a grease or a wax serving as a lubricant and binder for the fluffy particles results in a composition possessing excellent detergent and delicately abrasive properm ties for the cleaning of metal ware, glassware, porcelainware or surfaces having an enameled, glazed, or vitreous finish. Because of its extreme porosity, the aerogel is readily impregnated with and provides an excellent carrier for the oil, 15 grease, or wax with which it is incorporated. In addition, the relatively fragile structure of the aerogel readily breaks down under friction to release minute particles of the abrasive which are thoroughly distributed throughout the binding and lubricating medium. I

While it has been found that stearic acidserves as an excellent binder for the aerogel due to its penetrability into the pores of the latter and because of its excellent lubricating qualities, other materials may be employed either alone or in combination. For example, paraffin and the soaps are capable of use with good results. While silica aerogel is ideally suited as the abrasive in such detergent and polishing compositions, other aerogels, as referred to in the above-mentioned patent, may be employed,-such as alumina, nickel oxide, thoria, titania, stannic oxide, magnesium oxide, and chromic oxide. Aerogels of cellulose, collodion, gelatine, and albumin also have limited 5 applicability, when included with a waxy binder, as polishing compounds for special purposes.

By way of illustration, a buffing composition composed of equabparts of silica aerogel and stearic acid has been found suitable for the polishing of silverware. A composition of the above ingredients may be molded into sticks and applied to a bufling wheel in the customary manner. The porous aerogel becomes loaded with the stearic acid and by frictional disintegration of its porous structure is distributed upon the surface of the ware in'the form of a thin film held in suspension by the waxy stearic acid. There is hence no tendency for the composition to scratch the surface of the relatively soft metal to which it is applied.

It will be understood that by the term aerogel used throughout the specification and claims is meant an aerogel produced in accordance with the method of the above Kistler patent, which 56 patent is by reference incorporated as a part of this specification. This invention also contemplates the preparation of buffing and polishing compositions by successive replacements of the liquid forming the continuous phase of the gel. The continuous phase may be replaced by immersing the gel in successive baths of a liquid which is miscible with the liquid then forming the continuous phase. Thus the water in a hydro gel may be replaced with alcohol by immersion in the replacing liquid. The alcohol may be displaced by etherwhich in turn may be replaced, at least in part,

by ligroin.

A suitable method of replacing the ligroin with stearic acid involves the preparation of a slurry or suspension of ligroin gel in melted stearic acid. The ligroin is then distilled off while agitating the mixture.

The wide variation in properties obtainable makes the aerogels suitable for use alone as abrasives in a number of ways. The density and strength of the final product are dependent in large measure on the concentration of the'gel as originally formed and the subsequent treatment. Aerogels may be used either alone or in combination with other polishing agents such as insoluble 1 tooth powders.

sodium metaphosphate, phosphates calcium perborate, and calcium sulphate for tooth powders. When compounded with abrasives which tend to cake, such as dicalcium phosphate, it will be found that the mixture is free 2. A dentifrice comprising dicalcium ph os-.

phate and from 20 to of an aerogel.

3. A dentifrice comprising dicalcium phosphate and from 20 to 80% of silica areogel.

4. A dentifrice comprising dicalcium phosphate and from 20 to 80% of magnesia aerogel.

5. A dentifrice comprising dicalcium phosphate and from 20 to 80% of gelatin aerogel.

' SAMUEL S. KISTLER. 

